Metabolic Activity Assay Research Articles

Weak direct current exerts synergistic effect with antibiotics and reduces the antibiotic resistance: An in vitro subgingival plaque biofilm model.

Weak direct current (DC) exerts killing effect and synergistic killing effect with antibiotics in some specific bacteria biofilms. However, the potential of weak DC alone or combined with periodontal antibiotics in controlling periodontal pathogens and plaque biofilms remains unclear. The objective of this study was to investigate whether weak DC could exert the anti-biofilm effect or enhance the killing effect of metronidazole (MTZ) and/or amoxicillin-clavulanate potassium (AMC) on subgingival plaque biofilms, by constructing an in vitro subgingival plaque biofilm model. The pooled subgingival plaque and saliva of patients with periodontitis (n=10) were collected and cultured anaerobically on hydroxyapatite disks in vitro for 48 h to construct the subgingival plaque biofilm model. Then such models were stimulated with 0μA DC alone (20 min/12 h), 1000 μA DC alone (20 min/12 h), 16 μg/ml MTZ, 16 μg/ml AMC or their combination, respectively. Through viable bacteria counting, metabolic activity assay, quantitative real-time PCR absolute quantification and 16S rDNA sequencing analysis, the anti-biofilm effect of 1000 μA DC and enhanced killing effects of 1000 μA DC combined with antibiotics (MTZ, AMC or MTZ+AMC) were explored. The old subgingival plaque model (48 h) had no significant difference in total bacterial loads from subgingival plaque in situ, which achieved a similarity of 80%. The 1000 μA DC plus MTZ or AMC for 12 h showed a stronger synergistic killing effect than the same combination for 20 min. The metabolic activity was reduced to the lowest by DC plus MTZ+AMC, as 37.4% of that in the control group, while average synergistic killing effect reached 1.06 log units and average total bacterial loads decreased to 0.87 log units. Furthermore, the relative abundance of the genera Porphyromonas, Prevotella, Treponema_2, and Tannerella were decreased significantly. The presence of weak DC (1000 μA) improved the killing effect of antibiotics on subgingival plaque biofilms, which might provide a novel strategy to reduce their antibiotic resistance.

Targeting tumor-intrinsic PD-L1 suppresses the progression and aggressiveness of head and neck cancer by inhibiting GSK3β-dependent Snail degradation.

PD-L1 is an immune checkpoint protein that allows cells to evade T-cell-mediated immune responses. Herein, we uncover a tumor-intrinsic mechanism of PD-L1 that is responsible for the progression and aggressiveness of HNC and reveal that the extracts of a brown alga can target the tumor-intrinsic signaling pathway of PD-L1. The biological functions of PD-L1 in the proliferation and aggressiveness of HNC cells in vitro were examined by metabolic activity, clonogenic, tumorigenicity, wound healing, migration, and invasion assays. The clinical importance of PD-L1 in the prognosis of patients with HNC was analyzed by immunohistochemistry. The relationship between PD-L1 and EMT was confirmed via western blotting, qPCR, and immunocytochemistry. Through our in silico approach, we found that PD-L1 was upregulated in HNC and was correlated with an unfavorable clinical outcome in patients with HNC. PD-L1 was crucial for promoting tumor growth, both in vitro and in vivo. High expression of PD-L1 was closely correlated with LN metastasis in OSCC. PD-L1 facilitated the cytoskeletal reorganization and aggressiveness of HNC cells. Moreover, PD-L1 enhanced the EMT of HNC cells by regulating the Snail/vimentin axis. Consistently, MEIO suppressed the PD-L1/Snail/vimentin axis, thereby inhibiting the aggressiveness of HNC cells. Inhibition of PD-L1 induced by PD-L1 silencing or MEIO treatment caused Snail degradation through a GSK3β-dependent mechanism. The tumor-intrinsic function of PD-L1 could be attributed to the regulation of the GSK3β/Snail/vimentin axis. The discovery of MEIO targeting the tumor-intrinsic function of PD-L1 may prove particularly valuable for the development of novel and effective anticancer drug candidates for HNCs overexpressing PD-L1.

Cutaneous dysbiosis may amplify barrier dysfunction in patients with atopic dermatitis.

Atopic dermatitis (AD) is associated with cutaneous dysbiosis, barrier defects, and immune dysregulation, but the interplay between these factors needs further study. Early-onset barrier dysfunction may facilitate an innate immune response to commensal organisms and, consequently, the development of allergic sensitization. We aimed to compare the cutaneous microbiome in patients with active dermatitis with and without a history of childhood flexural dermatitis (atopic dermatitis). Next-gen Ion-Torrent deep-sequencing identified AD-associated changes in the skin bacterial microbiome ("bacteriome") and fungal microbiome ("mycobiome") of affected skin in swabs from areas of skin affected by dermatitis. Data were analyzed for diversity, abundance, and inter-kingdom correlations. Microbial interactions were assessed in biofilms using metabolic activity (XTT) assay and scanning electron microscopy (SEM), while host-pathogen interactions were determined in cultured primary keratinocytes exposed to biofilms. Increased richness and abundance of Staphylococcus, Lactococcus, and Alternaria were found in atopics. Staphylococcus and Alternaria formed robust mixed-species biofilms (based on XTT and SEM) that were resistant to antifungals/antimicrobials. Furthermore, their biofilm supernatant was capable of influencing keratinocytes biology (pro-inflammatory cytokines and structural proteins), suggesting an additive effect on AD-associated host response. In conclusion, microbial inter-kingdom and host-microbiome interactions may play a critical role in the modulation of atopic dermatitis to a greater extent than in non-atopic adults with allergic contact dermatitis.

Antibiofilm effect and mechanism of protocatechuic aldehyde against Vibrio parahaemolyticus.

This study investigated the effect of protocatechuic aldehyde (PCA) on Vibrio parahaemolyticus biofilm formation and its effects on gene expression. Crystal violet assay, metabolic activity assay, and fluorescence experiments were used to evaluate the antibiofilm activities of PCA and to reveal its possible antibiofilm mechanisms using transcriptomic analysis. The results indicated that the minimum antibacterial concentration of PCA against V. parahaemolyticus was 300 μg/mL. PCA (9.375 μg/mL) inhibited biofilm generation and adhesion of the mature biofilm. PCA (75 μg/mL) significantly reduced the metabolic viability of V. parahaemolyticus, reduced polysaccharide production, and inhibited cell surface flagella-mediated swimming and aggregation phenotypes. Meanwhile, transcriptome analysis showed that the key genes of V. parahaemolyticus expressed under PCA (75 μg/mL) inhibition were mainly related to biofilm formation (pfkA, galE, narL, and oppA), polysaccharide production and adhesion (IF, fbpA, and yxeM), and motility (cheY, flrC, and fliA). By regulating these key genes, PCA reduced biofilm formation, suppressed polysaccharide production and transport, and prevented the adhesion of V. parahaemolyticus, thereby reducing the virulence of V. parahaemolyticus. This study demonstrated that protocatechuic aldehyde can be used to control V. parahaemolyticus biofilm to ensure food safety.

Carbon Nanoparticles Extracted from Date Palm Fronds for Fluorescence Bioimaging: In Vitro Study.

Numerous studies have been reported on single- and multicolored highly fluorescent carbon nanoparticles (FCNPs) originating from various sources and their potential applications in bioimaging. Herein, multicolored biocompatible carbon nanoparticles (CNPs) unsheathed from date palm fronds were studied. The extracted CNPs were characterized via several microscopic and spectroscopic techniques. The results revealed that the CNPs were crystalline graphitic and hydrophilic in nature with sizes ranging from 4 to 20 nm. The unsheathed CNPs showed exemplary photoluminescent (PL) properties. They also emitted bright blue colors when exposed to ultraviolet (UV) light. Furthermore, in vitro cellular uptake and cell viability in the presence of CNPs were also investigated. The cell viability of human colon cancer (HCT-116) and breast adenocarcinoma (MCF-7) cell lines with aqueous CNPs at different concentrations was assessed by a cell metabolic activity assay (MTT) for 24 and 48 h incubations. The results were combined to generate dose-response curves for the CNPs and evaluate the severity of their toxicity. The CNPs showed adequate fluorescence with high cell viability for in vitro cell imaging. Under the laser-scanning confocal microscope, the CNPs with HCT-116 and MCF-7 cell lines showed multicolor fluorescence emissions, including blue, green, and red colors when excited at 405, 458, and 561 nm, respectively. These results prove that unsheathed CNPs from date palm fronds can be used in diverse biomedical applications because of their low cytotoxicity, adequate fluorescence, eco-friendly nature, and cheap production.

The Preparation and Biological Testing of Novel Wound Dressings with an Encapsulated Antibacterial and Antioxidant Substance.

Chronic wounds represent a significant socio-economic problem, and the improvement of their healing is therefore an essential issue. This paper describes the preparation and biological properties of a novel functionalized nanofiber wound dressing consisting of a polycaprolactone nanofiber carrier modified by a drug delivery system, based on the lipid particles formed by 1-tetradecanol and encapsulated gentamicin and tocopherol acetate. The cytotoxicity of extracts was tested using a metabolic activity assay, and the antibacterial properties of the extracts were tested in vitro on the bacterial strains Staphylococcus aureus and Pseudomonas aeruginosa. The effect of the wound dressing on chronic wound healing was subsequently tested using a mouse model. Fourteen days after surgery, the groups treated by the examined wound cover showed a lower granulation, reepithelization, and inflammation score compared to both the uninfected groups, a lower dermis organization compared to the control, a higher scar thickness compared to the other groups, and a higher thickness of hypodermis and bacteria score compared to both the uninfected groups. This work demonstrates the basic parameters of the safety (biocompatibility) and performance (effect on healing) of the dressing as a medical device and indicates the feasibility of the concept of its preparation in outpatient conditions using a suitable functionalization device.

Spermidine activates authophagy but does not rescue human neuroblastoma SH-SY5Y cells from effects of arginine starvation

Background. Neuroblastoma is a malignant tumor of the sympathetic nervous system common in early childhood. Autophagy is manifested in neuroblastoma cells at basal levels, but is often upregulated in cells of the aggressive neuroblastoma forms. The aim of the study was to evaluate effects of polyamine spermidine and deficiency of arginine on cell viability and autophagy regulation in cells of human neuroblastoma. Materials and Methods. The human neuroblastoma SH-SY5Y cell line was an experimental model for the MTT assay of metabolic activity and cell viability upon exposure to different concentrations of spermidine in complete and arginine-free media. Assessing autophagy induction under arginine deficiency and spermidine treatment was carried out using fluorescence microscopy of neuroblastoma cells labeled with autophagic lysosomes-staining dye monodancylcadaverine. Results and Discussion. It was found that arginine withdrawal abrogates proliferation of SH-SY5Y cells. In the presence of arginine precursor, citrulline, in arginine-free medium, SH-SY5Y cells could not proliferate and, therefore, are auxotrophic for arginine. SH-SY5Y cells were more sensitive to arginine starvation than to starvation for indispensible amino acids lysine or leucine. It was also revealed that spermidine at low concentrations of 5-10 μM did not affect SH-SY5Y cells viability irrespective of arginine availability. However, at 50 and higher concentrations this polyamine was highly cytotoxic in arginine-sufficient or deficient media. Analysis of autophagy induction by spermidine and under arginine starvation revealed an increase in the number of autophagic lysosomes in SH-SY5Y cells and additive effect of the two stimuli. Conclusion. The described experiments revealed that arginine deprivation abrogated proliferation, led to a decrease in cell viability and induced autophagy in human neuroblastoma SH-SY5Y cells. Spermidine at the concentrations of 5-10 μM, while upinducing autophagy, did not improve survival of SH-SY5Y cells under arginine deprivation, whereas at a concentration above 50 μM spermidine had a strong cytotoxic effect. The main observation of this study is that autophagy can be readily manipulated in neuroblastoma cells by simultaneous deprivation for arginine and spermidine treatment.

Highly tailorable gellan gum nanoparticles as a platform for the development of T cell activator systems

BackgroundT cell priming has been shown to be a powerful immunotherapeutic approach for cancer treatment in terms of efficacy and relatively weak side effects. Systems that optimize the stimulation of T cells to improve therapeutic efficacy are therefore in constant demand. A way to achieve this is through artificial antigen presenting cells that are complexes between vehicles and key molecules that target relevant T cell subpopulations, eliciting antigen-specific T cell priming. In such T cell activator systems, the vehicles chosen to deliver and present the key molecules to the targeted cell populations are of extreme importance. In this work, a new platform for the creation of T cell activator systems based on highly tailorable nanoparticles made from the natural polymer gellan gum (GG) was developed and validated.MethodsGG nanoparticles were produced by a water in oil emulsion procedure, and characterized by dynamic light scattering, high resolution scanning electronic microscopy and water uptake. Their biocompatibility with cultured cells was assessed by a metabolic activity assay. Surface functionalization was performed with anti-CD3/CD28 antibodies via EDC/NHS or NeutrAvidin/Biotin linkage. Functionalized particles were tested for their capacity to stimulate CD4+ T cells and trigger T cell cytotoxic responses.ResultsNanoparticles were approximately 150 nm in size, with a stable structure and no detectable cytotoxicity. Water uptake originated a weight gain of up to 3200%. The functional antibodies did efficiently bind to the nanoparticles, as confirmed by SDS-PAGE, which then targeted the desired CD4+ populations, as confirmed by confocal microscopy. The developed system presented a more sustained T cell activation over time when compared to commercial alternatives. Concurrently, the expression of higher levels of key cytotoxic pathway molecules granzyme B/perforin was induced, suggesting a greater cytotoxic potential for future application in adoptive cancer therapy.ConclusionsOur results show that GG nanoparticles were successfully used as a highly tailorable T cell activator system platform capable of T cell expansion and re-education.

Chitosan-poly(ethylene oxide) nanofibrous mat as a vaginal platform for tenofovir disoproxyl fumarate – The effect of vaginal pH on drug carrier performance

In the present work, a solution blow spun nanofibrous mat comprised of chitosan (CS) and poly(ethylene oxide) (PEO) was obtained as vaginal platform for tenofovir disoproxil fumarate (TDF) to prevent sexually transmitted infections. Apart from physicochemical and mechanical analysis, the specific steps involved studies on nanofibrous mat mucoadhesive and swelling characteristics upon pH fluctuations over the physiological range. Physicochemical analysis showed uniform drug distribution within the CS/PEO mat volume and pointed toward physical interactions between the drug and polymers. TDF-loaded CS/PEO nanofibrous mat was shown potentially safe when evaluated by the MTT metabolic activity and JC-1 assays in human vaginal epithelial cells VK2-E6/E7. In vitro antiviral studies indicated inhibition efficacy of TDF-CS/PEO nanofibrous mat toward HSV-2 virus and proved the SBS process does not change the microbicidal activity of drug molecule. Fluctuations in the physiological vaginal pH range of 3.8 to 5.0 substantially affected mucoadhesive and swelling behavior of chitosan which in turn impacted drug dissolution rate from polymer carrier. The rate of permeation and accumulation of TDF in vaginal tissue differed in response to vaginal pH. Faster drug permeation assessed at pH 5.0 suggests that an increase in vaginal pH could improve TDF bioavailability at earlier time points.

Determination of synergistic effect between roughness and surface chemistry on cell adhesion of a multilayer Si - Hydroxyapatite coating on Ti6Al4V obtained by magnetron sputtering

Ti alloys are widely used in the biomedical field because they have an adequate balance between mechanical properties, corrosion resistance and biocompatibility. However, when this material is incorporated in the human body, unfavorable reactions can be obtained which do not allow a good osseointegration due to the formation of a fibrous and non-adherent layer between the biomaterial and the bone, which can lead to failure or rejection of the implant. In this study, the influence of surface modification of Ti6Al4V alloy with a hydroxyapatite (HA) and silicon (Si) coating on its biological response in vitro was evaluated. The deposition process was performed by sputtering on two Ti6Al4V surfaces with different root mean square roughness values, the first one with 3.8 nm and the second one with 48.7 nm. The surface morphology of the coatings was observed by Scanning Electron Microscopy and Atomic Force Microscopy, the chemical composition was evaluated by X-ray Energy Dispersive Spectrometry and micro-Raman Spectroscopy. The in vitro biological response of the coatings was evaluated by cell metabolic activity assay and cell adhesion tests, using mouse mesenchymal stem cells. The control of the process parameters allowed obtaining a multilayer HA-Si coating with good compositional balance (Ca/P ratio very close to 1.67 and characteristic vibrations of the HA phase). Roughness values of 27 ± 5 nm and 52 ± 6 nm were obtained for the multilayer coatings obtained on Ti6Al4V (smooth surface) and Ti6Al4V (rough surface), respectively. Biological assays indicated a potentially non-toxic character of the coatings, moreover, the cell adhesion of Ti6Al4V was favored both by the incorporation of the HA-Si multilayer coating and by the increase in the roughness of the substrate.

S9.3d Antivirulence drug discovery to disarm Candida albicans with metabolites from myxobacteria.

S9.3 Drug resistance in emerging pathogenic fungi, September 23, 2022, 4:45 PM - 6:15 PM Candida albicans is an opportunistic fungal pathogen. While nearly 40%-60% of humans are colonized harmlessly by C. albicans, prolonged use of antibiotics or an immune-compromised status can lead to mucosal or deadly systemic candidiasis (Kumamoto et al., 2020). There are only three classes of antifungals available to physicians to treat and prevent severe Candidiasis. These drugs, which include polyenes, echinocandins, and azoles, protect the host by killing or inhibiting growth of C. albicans, thereby exerting a strong selective pressure toward drug resistance. Antivirulence drugs, by contrast, target virulence traits of pathogens without affecting their growth, making drug resistance less likely to evolve. We seek to discover novel antivirulence compounds against C. albicans that keep it at, or return it to, its baseline commensal state even under conditions that support pathogenicity. Bacteria have evolved a large repository of metabolites that can inhibit and modulate the behavior of other organisms in their environment. Clades like the predatory myxobacteria are untapped for potential antifungal and antivirulence drug discovery (Vij et al., 2021). We here screened ≈ 2800 crude extracts from myxobacteria in an in situ C. albicans-mammalian epithelial cell infection model. Typically, when oral epithelial cells (TR146) are infected by C. albicans, the fungus proliferates, forms hyphae, and invades and damages the monolayer. In our assay, we estimate the damage to epithelial cells by released lactate dehydrogenase. We also note changes to the growth and morphology of the fungus. Based on these readouts we assign antivirulence and antifungal ranks to each extract, and confirm top-ranked hits with an independent propidium iodide-based assay for host cell damage, and a colorimetric assay of fungal metabolic activity. We found that several of the top-ranked antifungal extracts also showed effects on a multi-drug resistant strain of C. auris. Using an established pipeline, we identified several of the antifungal and antivirulent bioactive components in these extracts. After scaling the production of promising lead compounds, we will test their drugability on clinical Candida spp. strains, and identify their mode of action using large-scale Candida spp. knock-out libraries and multi-omics approaches. Our tested extracts are likely to contain new classes of non-toxic antifungals that can potentially treat infections by multi-drug resistant fungi. We identified and confirmed several myxobacteria extracts that protected mammalian epithelial cells without severely affecting the fungus’ growth, which are, therefore, considered antivirulent.SourcesKumamoto, C.A., Gresnigt, M.S., Hube, B., 2020. The gut, the bad and the harmless: Candida albicans as a commensal and opportunistic pathogen in the intestine. Curr. Opin. Microbiol. 56, 7–15. https://doi.org/10.1016/j.mib.2020.05.006Vij, R., Hube, B., Brunke, S., 2021. Uncharted territories in the discovery of antifungal and antivirulence natural products from bacteria. Comput. Struct. Biotechnol. J. 19, 1244–1252. https://doi.org/10.1016/j.csbj.2021.02.003

P002 Antifungal activity of antimicrobial synthetic peptides against Candida species of public health importance

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PMBackgroundCandidiasis is one of the most frequent opportunistic infections in immunosuppressed and/or hospitalized patients. In countries like Colombia, candidiasis is associated with a mortality rate of ∼ 46%. Growing pharmacological resistance of Candida spp., and the appearance of the emerging pathogen Candida auris, have turned candidiasis into a major public health problem. Different types of antimicrobial peptides have been investigated as a therapeutic alternative to control candidiasis effectively and safely.ObjectiveThis work aimed at evaluating the in vitro antifungal activity of three synthetic antimicrobial peptides (35 409, 1609, and 29 009) obtained from Plasmodium falciparum Rif1 protein against C. auris, C. albicans, C. glabrata, C. parapsilosis, C. krusei, and C. tropicalis, species with worldwide clinical importance.MethodsThe minimum inhibitory concentrations (MIC) of the three peptides against Candida species were determined by the plate microdilution method; the peptides’ effect on biofilm formation in C. auris and C. albicans species was also evaluated through the XTT metabolic activity assay. Additionally, the structural damages in C. auris and C. albicans caused by the action of the peptides were observed by transmission electron microscopy (TEM) and finally, the in vitro peptides’ cytotoxicity against L929 murine fibroblasts was verified.ResultsOur findings showed that the three peptides herein evaluated, displayed antifungal activity in both planktonic and sessile Candida cells. Likewise, the TEM evidenced morphological alterations induced by the peptides, both in the membrane and at the intracellular level of the yeasts. As well, total safety against the murine cell line L929 with 24 h of treatment was observed.ConclusionsFrom these results, we conclude that the antimicrobial peptides 35 409, 1609, and 29 009 are potential therapeutic alternatives against the most important Candida species in Colombia and the world.

Understanding the Role of Nitronate Monooxygenases in Virulence of the Human Fungal Pathogen Aspergillus fumigatus.

Aspergillus fumigatus is the leading cause of the fungal invasive disease called aspergillosis, which is associated with a high mortality rate that can reach 50% in some groups of immunocompromised individuals. The increasing prevalence of azole-resistant A. fumigatus isolates, both in clinical settings and the environment, highlights the importance of discovering new fungal virulence factors that can potentially become targets for novel antifungals. Nitronate monooxygenases (Nmos) represent potential targets for antifungal compounds as no orthologs of those enzymes are present in humans. Nmos catalyse the denitrification of nitroalkanes, thereby detoxifying these mediators of nitro-oxidative stress, and therefore we tested whether Nmos provide protection for A. fumigatus against host-imposed stresses at sites of infection. The results of inhibition zone assays indicated that Nmo2 and Nmo5 are not essential for the oxidative stress resistance of A. fumigatus in vitro. In addition, the resazurin-based metabolic activity assay revealed that the growth of mutants lacking the nmo2 or nmo5 genes was only slightly reduced in the presence of 0.05 mM peroxynitrite. Nevertheless, both Nmo2 and Nmo5 were shown to contribute to defense against murine bone marrow-derived macrophages, and this was no longer observed when NADPH oxidase, the main generator of reactive oxygen species during infection, was inhibited in macrophages. Furthermore, we revealed that Nnmos promote the virulence of the fungus in the Galleria mellonella model of infection. Both nmo2 and nmo5 knock-out strains were less virulent than the wild-type control as recorded 72 h post-infection. Our results indicate that Nmos play a role in the virulence of A. fumigatus.

Abstract 5221: The first-in-class ERK inhibitor ulixertinib (BVD-523) shows activity in MAPK-driven pediatric low-grade glioma models as single agent and in combination with MEK inhibitors or senolytics

Abstract Ulixertinib (BVD-523) is a well-tolerated, orally delivered, catalytic ERK1/2 inhibitor, which has shown promising responses in adult patients with mitogen-activated protein kinase (MAPK)-driven solid tumors. Pediatric low grade gliomas (pLGGs) are the most common pediatric brain tumors, with the most frequent driving alterations (KIAA:BRAF fusion, BRAF V600E mutation) occurring in the MAPK pathway. To investigate the anti-tumoral activity of ulixertinib in pLGG, cell lines recapitulating both main MAPK alterations were used: DKFZ-BT66 (pilocytic astrocytoma; KIAA:BRAF fusion) and BT40 (pleomorphic xanthoastrocytoma; BRAF V600E mutation and CDKN2A/B deletion). The potential synergism of combinations with MEK inhibitors, senolytics, and chemotherapy was investigated in vitro using metabolic activity and MAPK activity assays. The most promising combinations were validated in vitro by analysis of viable, dead, and apoptotic cells through high-content microscopy. The most clinically relevant combinations were further validated in vivo: 1) in two zebrafish embryo models (respectively, BT40 and DKFZ-BT66 yolk sac injection) and 2) in NSG mice (BT40 orthotopic PDX) including in vivo pharmacokinetic and -dynamic analyses. Our data demonstrate ulixertinib’s ability to inhibit MAPK pathway activity in all used models. Ulixertinib treatment reduced cell viability in the BRAF V600E mutated cell line at a remarkably low concentration of 62.7 nM (compared to other cell lines’ IC50 from the Genomics of Drug Sensitivity in Cancer database). In vivo pharmacokinetic and -dynamic analyses showed good penetrance of the drug into mouse brain tissue, with concentrations above the in vitro IC50 and reduction of MAPK activity as assessed by Western blot. Furthermore, ulixertinib treatment slowed tumor growth and significantly increased survival in NSG mice with orthotopic BT40 xenografts. Ulixertinib showed indications for anti-proliferative synergy in vitro, according to the Loewe and Bliss independence models, in combination with MEK inhibitors (trametinib, binimetinib) or senolytics (navitoclax, A1331852). Combinations with chemotherapy (carboplatin, vinblastine) were at most additive. Indications for synergy with binimetinib and navitoclax were confirmed in the zebrafish embryo xenograft models for both MAPK-altered backgrounds. The combination of ulixertinib with navitoclax was further investigated in the BT40 PDX mouse model, where tumor growth and survival were comparable to ulixertinib monotherapy. In conclusion, our data indicate a strong potential for ulixertinib as a clinically relevant therapeutic option for the treatment of pLGG to be further investigated in upcoming clinical trials. Potential synergism with MEK inhibitors and senolytics was noted and warrants further investigation. Citation Format: Romain Sigaud, Lisa Rösch, Charlotte Gatzweiler, Julia Benzel, Laura von Soosten, Heike Peterziel, Sara Najafi, Simay Ayhan, Nina Hofmann, Kathrin I. Förster, Jürgen Burhenne, Rémi Longuespée, Cornelis M. van Tilburg, David T. Jones, Stefan M. Pfister, Deborah Knoerzer, Brent Kreider, Max Sauter, Kristian W. Pajtler, Marc Zuckermann, Ina Oehme, Olaf Witt, Till Milde. The first-in-class ERK inhibitor ulixertinib (BVD-523) shows activity in MAPK-driven pediatric low-grade glioma models as single agent and in combination with MEK inhibitors or senolytics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5221.

Abstract 1098: Structure-activity relationship of pentacyclic triterpenes against chemoresistance and metastasis on non-small lung adenocarcinoma cells

Abstract Lung cancer is the second most common and leading cause of cancer-related death worldwide, 85% of these cases being non-small cell lung carcinoma (NSCLC). Although chemotherapy is the first-line treatment for lung cancer, its effectiveness is hampered by the dose-limiting toxic effects, chemoresistance, and metastatic process. Recently, plant-derived cyclic triterpenoids (eg, cholesterol-structure like compounds) have shown a wide spectrum of pharmacological activities, especially their potential against different cancer cells. Herein, we investigated the structure-activity relationship of several pentacyclic triterpenes: oleanolic acid (OleA), ursolic acid (UrA), betulinic acid (BeA), Asiatic acid (AsA), betulin (BeN), lupeol (Lupe), diosgenin (Dio), stigmasterol (Stg) and β-sitosterol (β-Sito) on NSCLC A549 cells. From our studies, the IC50 for OleA, UrA, BeA, AsA, BeN, Lupe, Dio were in the low µM range (from 10-75 µM) after 24h of incubation. β-Sito and Stg did not show any significant cytotoxic pattern in this µM range. In addition, BeA showed the highest cytotoxic pattern in these cells. We performed metabolic activity assays to determine the mechanism of action of these triterpenes. Mitochondrial membrane and caspases activity assays showed that all the cytotoxic triterpenes induced activation of caspase-3 and decline in the mitochondrial potential, except BeA and AsA. Our results also show that all the cytotoxic triterpenes disrupt cell membrane, except for OleA. However, there is no reactive oxygen species production for all of them. Gene expression assays of chemoresistance- and metastasis-related genes (EGFR, VEGF, MMP9, Pgp, TP53, NDRG1, CHD4) using qPCR demonstrated the downregulation of all of these genes after the incubation with the cytotoxic triterpenes. These results demonstrated that even slight structural changes in these triterpenes could influence the cytotoxic and metabolic pathways responses. This study opens promising perspectives for further research on the role of phytochemical triterpenes, which ultimately will contribute to a more rational application in lung cancer therapy. Citation Format: Yamixa Delgado, Daraishka Perez, Grace Torres. Structure-activity relationship of pentacyclic triterpenes against chemoresistance and metastasis on non-small lung adenocarcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1098.

High-throughput metabolomics reveals dysregulation of hydrophobic metabolomes in cancer cell lines by Eleusine indica

Eleusine indica, which is used in traditional medicine, exhibits antiproliferative activity against several cancer cell lines. However, metabolomic studies to evaluate the metabolite changes induced by E. indica in cancer cells are still lacking. The present study investigated the anticancer effects of a root fraction of E. indica (R-S5-C1-H1) on H1299, MCF-7, and SK-HEP-1 cell lines and analyzed metabolic changes in the treated cancer cells using ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS). Cell metabolic activity assays demonstrated that the cell viability of the three cancer cell lines was significantly reduced following treatment with R-S5-C1-H1, with half-maximal inhibitory concentrations values of 12.95 µg/mL, 15.99 µg/mL, and 13.69 µg/mL at 72 h, respectively. Microscopy analysis using Hoechst 33342 and Annexin V fluorescent dyes revealed that cells treated with R-S5-C1-H1 underwent apoptotic cell death, while chemometric analysis suggested that apoptosis was triggered 48 h after treatment with R-S5-C1-H1. Deconvoluted cellular metabolomics revealed that hydrophobic metabolites were significantly altered, including triacylglycerols, phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and ceramide, suggesting that apoptosis induction by R-S5-C1-H1 potentially occurred through modulation of phospholipid synthesis and sphingolipid metabolism. These metabolomic profiling results provide new insights into the anticancer mechanisms of E. indica and facilitate the overall understanding of molecular events following therapeutic interventions.

Intracellular and Extracellular Antifreeze Protein Significantly Improves Mammalian Cell Cryopreservation.

Cell cryopreservation is an essential part of the biotechnology, food, and health care industries. There is a need to develop more effective, less toxic cryoprotective agents (CPAs) and methods, especially for mammalian cells. We investigated the impact of an insect antifreeze protein from Anatolica polita (ApAFP752) on mammalian cell cryopreservation using the human embryonic kidney cell line HEK 293T. An enhanced green fluorescent protein (EGFP)-tagged antifreeze protein, EGFP–ApAFP752, was transfected into the cells and the GFP was used to determine the efficiency of transfection. AFP was assessed for its cryoprotective effects intra- and extracellularly and both simultaneously at different concentrations with and without dimethyl sulfoxide (DMSO) at different concentrations. Comparisons were made to DMSO or medium alone. Cells were cryopreserved at −196 °C for ≥4 weeks. Upon thawing, cellular viability was determined using trypan blue, cellular damage was assessed by lactate dehydrogenase (LDH) assay, and cellular metabolism was measured using a metabolic activity assay (MTS). The use of this AFP significantly improved cryopreserved cell survival when used with DMSO intracellularly. Extracellular AFP also significantly improved cell survival when included in the DMSO freezing medium. Intra- and extracellular AFP used together demonstrated the most significantly increased cryoprotection compared to DMSO alone. These findings present a potential method to improve the viability of cryopreserved mammalian cells.

Antiplanktonic and Antibiofilm Activity of Rheum palmatum against Streptococcus oralis and Porphyromonas gingivalis.

Periodontitis and peri-implantitis are inflammatory conditions with a high global prevalence. Oral pathogens such as Porphyromonas gingivalis play a crucial role in the development of dysbiotic biofilms associated with both diseases. The aim of our study was to identify plant-derived substances which mainly inhibit the growth of “disease promoting bacteria”, by comparing the effect of Rheum palmatum root extract against P. gingivalis and the commensal species Streptococcus oralis. Antiplanktonic activity was determined by measuring optical density and metabolic activity. Antibiofilm activity was quantified using metabolic activity assays and live/dead fluorescence staining combined with confocal laser scanning microscopy. At concentrations of 3.9 mg/L, R. palmatum root extract selectively inhibited planktonic growth of the oral pathogen P. gingivalis, while not inhibiting growth of S. oralis. Selective effects also occurred in mature biofilms, as P. gingivalis was significantly more stressed and inhibited than S. oralis. Our studies show that low concentrations of R. palmatum root extract specifically inhibit P. gingivalis growth, and offer a promising approach for the development of a potential topical agent to prevent alterations in the microbiome due to overgrowth of pathogenic P. gingivalis.

Insight into the enhancing mechanism of silica nanoparticles on denitrification: Effect on electron transfer and microbial metabolism

Although silica nanoparticles (SiNPs) are produced in large numbers for industrial manufacturing and engineering applications, the effect of SiNPs on biotransformation in the environment is still not clear. In the current study, the effect of SiNPs in enhancing denitrification was investigated, and its mechanism was explored from the perspectives of electron transfer, microbial metabolism and bacterial community structure for the first time. Batch experiments showed that a concentration of SiNPs ranging from 0.05 to 5 g/L enhanced the bioreduction of nitrate. The mechanism study showed that SiNPs accelerated the extracellular electron transfer in the denitrification process due to their electron donating capacity, bonding action, and the secretion of more electron shuttles. During the denitrification process, SiNPs promoted metabolic activity, which mainly consists of promoting enzyme activities and electron transport system activity; these metabolic activity assays were positively correlated with SiNPs according to the structural equation modeling analysis. Moreover, SiNPs affected the composition of the microbial community, including denitrifying functional bacteria, silicon-activating bacteria and electron transfer active bacteria exhibiting a synergistic symbiosis. In addition, it was shown, by investigating two functional group-modified SiNPs, that the carboxyl modified SiNPs had the potential to be applied in nitrogen removal due to their performance and non-toxicity. This study presented a better insight into the role of SiNPs in biological transformation.

New Approach against Chondrosoma Cells-Cold Plasma Treatment Inhibits Cell Motility and Metabolism, and Leads to Apoptosis.

(1) Background: Chondrosarcoma (CS) is a malignant primary bone tumor with a cartilaginous origin. Its slow cell division and severely restricted vascularization are responsible for its poor responsiveness to chemotherapy and radiotherapy. The decisive factor for the prognosis of CS patients is the only adequate therapy—surgical resection. Cold atmospheric pressure plasma (CAP) is emerging as a new option in anti-cancer therapy. Its effect on chondrosarcomas has been poorly investigated. (2) Methods: Two CS cell lines—SW 1353 and CAL 78—were used. Various assays, such as cell growth kinetics, glucose uptake, and metabolic activity assay, along with two different apoptosis assays were performed after CAP treatment. A radius cell migration assay was used to examine cell motility. (3) Results: Both cell lines showed different growth behavior, which was taken into account when using the assays. After CAP treatment, a reduction in metabolic activity was observed in both cell lines. The immediate effect of CAP showed a reduction in cell numbers and in influence on this cell line’s growth rate. The measurement of the glucose concentration in the cell culture medium showed an increase after CAP treatment. Live-dead cell imaging shows an increase in the proportion of dead cells over the incubation time for both cell lines. There was a significant increase in apoptotic signals after 48 h and 72 h for both cell lines in both assays. The migration assay showed that CAP treatment inhibited the motility of chondrosarcoma cells. The effects in all experiments were related to the duration of CAP exposure. (4) Conclusions: The CAP treatment of CS cells inhibits their growth, motility, and metabolism by initiating apoptotic processes.